Swagelok® 40G Series Ball Valve Technical Bulletin
The
Swagelok® 40 series one-piece instrumentation ball valve has
performed reliably for nearly 40 years in multiple industries.
Swagelok has modified the valve construction and developed an
innovative assembly process. The result is the new 40G series ball
valve, which features an expanded operating temperature rating,
improved thermal cycling capabilities, and reduced potential for
leaks.
Using a patent-pending seal design, the 40G series ball valve
resists packing deformation, or “cold-flow,” for increased thermal
performance and improved leak resistance. Its expanded temperature
range, from –65 to 300°F (–53 to 148°C), meets application demands
for both environmental and heated-process applications (Figure 1).
Figure 1.
The 40G Series ball valve’s expanded temperature range meets
application demands for environmental and heated-process applications.
Environmental
– applications in which the valve experiences thermal cycling due to
fluctuating outside temperatures, such as:
- Outdoor process instrumentation systems
- Grab sample systems
- Sample conditioning systems
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Heated-process
– applications in which heat is applied to the process stream,
such as:
- Sample conditioning systems in heated enclosures
- Laboratory applications:
- Micro-reactors
- Test hoods
- Pilot plants
- Research and development facilities
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The 40G series valve is capable of operating with minimal service
adjustments and maintenance required. Several aspects of the 40G series
valve’s single-piece seal design contribute to its enhanced thermal
performance and low-maintenance characteristics (Figure 2):
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1. Hex-style packing bolt
2. Live-loaded packing system
3. Packing gland
4. Encapsulated patent-pending single-piece packing design
5. Enlarged trunnions
6. Trunnion pocket
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Figure 2.
Cross-section of the 40G series ball valve
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- An encapsulated patent-pending single-piece packing design
- Enlarged trunnions;
- A live-loaded packing system;
- New TFM® packing material; and
- A trunnion pocket.
In addition, a new patent-pending assembly method ensures
valve-to-valve consistency and reduces the need for packing adjustments
in the field.
The 40G series valve is designed to provide a cycle life equal to
or better than the 40 series valve in existing applications. It has
equivalent dimensions to the 40 series, making 40G series valves
dimensionally interchangeable with 40 series valves.
The new 40G series ball valve is available as a two-way valve for
shut-off service in both a straight and angle pattern, as well as a
three-way valve for switching service. The valves can be used in
applications with working pressures up to 3,000 psig (206 bar).
The 40G series will replace several part numbers in the standard
and live-loaded 40 series product lines, including the stainless steel
41, 42, and 43 models with 1/16 to 3/8 in. and 3 to 8 mm end
connections. The existing 44 and 45 models will not change at this time.
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Figure 3
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Encapsulated Patent-Pending Single-Piece Packing
The packing creates a functional seal inside the valve cavity and
is designed to handle temperature fluctuations while limiting the
potential for leaks. The 40G series ball valve utilizes an encapsulated
single-piece packing to house the ball and trunnion portion of the valve
ball stem for an uninterrupted, highly leak-resistant seal.
The 40G series stem is assembled into the single-piece
encapsulated packing. This subassembly is then pressed into the valve
cavity. The encapsulated packing completely surrounds the ball stem,
minimizing damage during actuation and thermal cycling. (Figure 3)
Enlarged Trunnions
Packing material tends to deform with temperature changes,
softening as temperatures rise and stiffening as temperatures fall. This
expansion and contraction allows the packing material to flow or extrude
into voids, or “dead spaces,” within the packing cavity or possibly even
flow outside of the valve’s packing cavity.
Swagelok has decreased the amount of packing material in the 40G
series valve’s packing cavity. To consume volume in the packing cavity
with material other than the TFM packing, Swagelok added an additional
trunnion to the 40G series valve’s 316 stainless steel ball stem. In
addition, Swagelok enlarged the diameter of the trunnions to displace
more packing volume.
Live-Loaded Packing System
After top loading the packing and stem subassembly into the
packing cavity, 40G series valve assemblers place a packing gland over
the valve stem. This gland slides over the upper trunnion to rest
directly on top of the packing material. With a close fit around the
trunnion and within the valve cavity, the gland fully contains the
packing.
A series of disc springs rests on top of the packing gland and is
secured by a packing bolt. The springs create a “live load” that is
transferred to the gland and, subsequently, to the packing. The “live
load” serves to maintain consistent sealing pressure on the packing
through temperature fluctuations and compensate for wear.
TFM Packing Material
The 40G series valve features a modified PTFE packing material
known as TFM®, an upgrade from the PTFE packing material in the 40
series valve. TFM has a higher resistance to cold-flow deformation
during thermal cycling compared to standard PTFE.
Trunnion Pocket
Swagelok added a trunnion pocket in the bottom of the 40G series
valve body. It serves as a deterrent to cold-flow and minimizes packing
extrusion.
Innovative Assembly Method
In the patent-pending assembly process – known as the direct-load
assembly method –assemblers add the series of disc springs over the ball
stem. Then they compress the springs to a specific load using a special
direct load method. The packing bolt is fastened to a specific point.
The direct load tool is then removed, and the secured packing bolt
maintains the valve load.
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Figure 4.
Internal view of the 40G series ball valve
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Additional Design Improvements
The 40G series ball valve features additional design
enhancements, including a hex-style packing bolt and modifications to
the handle material and design.
The 40G series valve’s design and construction minimize the need
for packing bolt adjustments in the field. However, the need for
adjustments over time exists in some applications. The hex on the 40G
series valve packing bolt (Figure 4) can be tightened by a standard
deep-well socket wrench, which simplifies field adjustments.
All 40G series valve handle inserts are now made of powdered
metal 300 series stainless steel. A double-flat stem handle is now
standard on all 40G series valves.